Beam management for multi-TRP

ABSTRACT

Methods and apparatus for beam management are disclosed. A WTRU may include a plurality of antenna panels, each antenna panel comprising a plurality of antennas configured to transmit on directional transmit (TX) beams. The WTRU may send, to a transmission reception point (TRP), antenna panel capability information for the plurality of antenna panels and receive a reference signal (RS) configuration for configuring RS resource sets. The WTRU may send an RS transmission trigger frame identifying triggered RS resource sets from the configured RS resource sets. The WTRU may identify a set of antenna panels to be used with the triggered RS resource sets. The WTRU may determine an UL TX beam sweeping mode and an association between the triggered RS resources sets and the set of antenna panels. The WTRU may perform UL beam sweeping using the triggered RS resource sets and associated set of antenna panels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage, under 35 U.S.C. § 371, ofInternational Application No. PCT/US2019/046826 filed Aug. 16, 2019,which claims the benefit of U.S. Provisional Application No. 62/765,091filed Aug. 17, 2018, the contents of which are incorporated herein byreference.

BACKGROUND

Third Generation Partnership Project (3GPP) standards discussions defineseveral deployment scenarios such as indoor hotspot, dense urban, rural,urban macro, and high speed. Based on general requirements set out byInternational Telecommunication Union Radio communication Sector(ITU-R), Next Generation Mobile Networks (NGMN) and 3GPP, a broadclassification of the use cases for emerging Fifth Generation (5G) NewRadio (NR) systems may be classified as enhanced mobile broadband(eMBB), massive machine type communications (mMTC) and ultra-reliableand low latency communications (URLLC). These use cases focus on meetingdifferent performance requirements such as higher data rate, higherspectrum efficiency, low power and higher energy efficiency, and/orlower latency and higher reliability. A wide range of spectrum bands,for example in the range of 700 MHz to 80 GHz, are being considered fora variety of deployment scenarios, that include licensed and unlicensedspectrum.

SUMMARY

Methods and apparatus for a multi-panel wireless transmit and/or receiveunit (WTRU) to perform uplink (UL) beam sweeping for uplink (UL) beammanagement are disclosed. The WTRU may include a plurality of antennapanels, each antenna panel comprising a respective plurality of antennasand configured to transmit on a respective plurality of directionaltransmit (TX) beams. The WTRU may send, to a transmission receptionpoint (TRP), antenna panel capability information for the plurality ofantenna panels and receive a reference signal (RS) configuration forconfiguring RS resource sets. The WTRU may send an RS transmissiontrigger frame identifying triggered RS resource sets from the configuredRS resource sets. The WTRU may identify a set of antenna panels from theplurality of antenna panels to be used with the triggered RS resourcesets based on at least one of the RS configuration or the RStransmission trigger frame. The WTRU may determine an UL TX beamsweeping mode based on the triggered RS resources sets and the set ofantenna panels and an association between the triggered RS resourcessets and the set of antenna panels. The WTRU may perform UL beamsweeping using the triggered RS resource sets and the set of antennapanels according to the association between the triggered RS resourcessets and the set of antenna panels.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawings,wherein like reference numerals in the figures indicate like elements,and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wireless transmitand/or receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 shows a diagram of an example massive antenna model for a WTRU(or gNB);

FIG. 3 shows a signaling diagram of an example beam sweeping procedureincluding separate and sequential (in time) UL TX beam sweeping at theWTRU among different WTRU antenna panels;

FIG. 4 shows a signaling diagram of an example beam sweeping procedureincluding joint/simultaneous (in time) UL TX beam sweeping at the WTRUamong different WTRU antenna panels;

FIG. 5 is a flow diagram of an example beam sweeping mode selection andantenna panel association procedure for multi-TRP based SRStransmissions using SRS resources, which may be part of an UL beammanagement procedure;

FIG. 6 shows a frame format of an example DCI frame that may be used asan SRS transmission trigger frame;

FIG. 7 shows a signaling diagram of an example beam sweeping procedureincluding simultaneous and sequential UL TX beam sweeping at the WTRUamong different WTRU antenna panels;

FIG. 8 shows a signaling diagram of an example beam sweeping procedureincluding simultaneous UL TX beam sweeping at the WTRU among differentWTRU antenna panels using different SRS resources within an SRS resourceset;

FIG. 9A shows a network diagram of an example beam pair link refinement;

FIG. 9B shows a network diagram of another example beam pair linkrefinement;

FIG. 10 shows a signaling diagram of an example beam sweeping procedureincluding configuration of reporting periodicity to reduce latency ofbeam training;

FIG. 11 shows a signaling diagram of an example beam sweeping procedureincluding appropriate configuration of reporting periodicity;

FIG. 12 shows a signaling diagram of an example DL RX beam sweepingprocedure at the WTRU;

FIG. 13A shows a network diagram of an example network configurationwhere different transmission power is used from different TRP panels;

FIG. 13B shows a network diagram of an example network configurationwhere different transmission power is used from different TRPs;

FIG. 14A shows a network diagram of an example network configurationwhere multiple DL TX beams at TRPs correspond to the same DL RX beams atthe WTRU; and

FIG. 14A shows a network diagram of an example network configurationwhere multiple DL TX beams at TRPs correspond to different DL RX beamsat the WTRU.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit and/or receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 102 a, 102 b, 102 c, 102 d, any of which may be referred to as a“station” and/or a “STA”, may be configured to transmit and/or receivewireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106/115, the Internet110, and/or the other networks 112. By way of example, the base stations114 a, 114 b may be a base transceiver station (BTS), a Node-B, an eNodeB, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller,an access point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit and/or receive element 122, a speaker/microphone 124, akeypad 126, a display/touchpad 128, non-removable memory 130, removablememory 132, a power source 134, a global positioning system (GPS)chipset 136, and/or other peripherals 138, among others. It will beappreciated that the WTRU 102 may include any sub-combination of theforegoing elements while remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit and/or receive element 122. WhileFIG. 1B depicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit and/or receive element 122 may be configured to transmitsignals to, or receive signals from, a base station (e.g., the basestation 114 a) over the air interface 116. For example, in oneembodiment, the transmit and/or receive element 122 may be an antennaconfigured to transmit and/or receive RF signals. In an embodiment, thetransmit and/or receive element 122 may be an emitter/detectorconfigured to transmit and/or receive IR, UV, or visible light signals,for example. In yet another embodiment, the transmit and/or receiveelement 122 may be configured to transmit and/or receive both RF andlight signals. It will be appreciated that the transmit and/or receiveelement 122 may be configured to transmit and/or receive any combinationof wireless signals.

Although the transmit and/or receive element 122 is depicted in FIG. 1Bas a single element, the WTRU 102 may include any number of transmitand/or receive elements 122. More specifically, the WTRU 102 may employMIMO technology. Thus, in one embodiment, the WTRU 102 may include twoor more transmit and/or receive elements 122 (e.g., multiple antennas)for transmitting and receiving wireless signals over the air interface116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit and/or receive element 122 and todemodulate the signals that are received by the transmit and/or receiveelement 122. As noted above, the WTRU 102 may have multi-modecapabilities. Thus, the transceiver 120 may include multipletransceivers for enabling the WTRU 102 to communicate via multiple RATs,such as NR and IEEE 802.11, for example.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit 139 toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WRTU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 10 is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 10 , the eNode-Bs160 a, 160 b, 160 c may communicate with one another over an X2interface.

The CN 106 shown in FIG. 10 may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-ab, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

Multiple antenna techniques such as MIMO, and variations of MIMOincluding Single Input Multiple Output (SIMO) and Multiple Input SingleOutput (MISO) techniques, have contributed significantly to theadvancement of telecommunications. MIMO techniques deliver benefits suchas providing diversity gain, multiplexing gain, beamforming, and/orarray gain. In the cellular communication paradigm, where all WTRUs maycommunicate with a single central node, the use of MU-MIMO may increasethe system throughput by facilitating the transmission (and/orreception) of multiple data streams to different WTRUs at the same timeon the same and/or overlapping set of resources in time and/orfrequency. In the SU-MIMO case, the central node may transmit (and/orreceive) multiple data streams to multiple WTRUs, and in the MU-MIMOcase the central node may transmit (and/or receive) multiple datastreams to multiple WTRUs.

Multiple antenna transmission at millimeter wave frequencies may differslightly from sub-6 GHz multiple antenna techniques. This is due to thedifferent propagation characteristics at millimeter wave frequencies andthe possibility of the gNB/WTRU having a limited number of radiofrequency (RF) chains compared with antenna elements.

FIG. 2 shows a diagram of an example massive antenna model 200 for aWTRU (or gNB). The example massive antenna model 200 may be configuredwith M_(g) antenna panels per vertical dimension and N_(g) antennapanels per horizontal dimension, where each antenna panel may beconfigured with N columns and M rows of antenna elements with or withoutpolarization. P may be the number of polarizations used, d_(g,V) may bethe vertical spacing between antenna panels, d_(g,H) may be thehorizontal spacing between antenna panels, d_(V) may be the verticalspacing between antennas, d_(H) may be the horizontal spacing betweenantennas, and λ may be the wavelength of the interfered with frequencyband. The timing and phase may or may not be calibrated across panelsalthough multiple panels may be equipped in the same eNB. In an example,the baseline massive antenna configuration may be different according tothe operating frequency band, as listed in Table 1.

TABLE 1 Example baseline massive antenna configuration for dense urbanand urban macro scenarios At 4 GHz At 30 GHz At 70 GHz Dense urban andurban Dense urban and urban Dense urban: macro: macro: Baseline: (M, N,P, M_(g), N_(g)) = (M, N, P, M_(g), N_(g)) = (M, N, P, M_(g), N_(g)) =(8, 16, 2, 2, 2) (8, 8, 2, 1, 1) (4, 8, 2, 2, 2) (d_(V), d_(H)) = (0.5,0.5)λ (d_(V), d_(H)) = (0.8, 0.5)λ (d_(V), d_(H)) = (0.5, 0.5)λ(d_(g, V), d_(g, H)) = (4.0, 8.0) (d_(g, V), d_(g, H)) = (2.0, 4.0)λ Asingle panel 4 panels 4 panels 64 elements per Polarization 32 elementsper Polarization 128 elements per Polarization Total 128 elements Total256 elements Total 1024 elements

Precoding at millimeter wave (mmW) frequencies may be digital, analog ora hybrid of digital and analog. Digital precoding is precise and can becombined with equalization. Digital precoding enables single user (SU),multi-user (MU) and multi-cell precoding and is similar to that used insub 6 GHz, for example in IEEE 802.11n and beyond and in 3GPP LTE andbeyond. However, at mmW frequencies, the presence of a limited number ofRF chains compared to the number of antenna elements and the sparsenature of the channel may complicate the use of digital beamforming.Analog beamforming may overcome the issues arising from a limited numberof RF chains by using analog phase shifters on each antenna element. Forexample, analog phase shifters may be used in IEEE 802.11ad during thesector level sweep (SLS) p (which identifies the best sector), beamrefinement (which refines the sector to an antenna beam) and/or beamtracking (which adjusts the sub-beams over time to take into account anychange in the channel). In hybrid beamforming, the precoder may bedivided between analog and digital domains. Each of the analog anddigital domains may include precoding and combining matrices withdifferent structural constraints (e.g. constant modulus constraint forcombining matrices in the analog domain). Using analog and digitaldomains may result in a compromise between hardware complexity andsystem performance. Hybrid beamforming may be able to achieve digitalprecoding performance due to the sparse nature of channel and maysupport multi-user/multi-stream multiplexing. However, hybridbeamforming may be limited by the number of RF chains, which may not bean issue because mmW channels are sparse in the angular domain.

The use of higher band frequencies (e.g., mmW band, Frequency Range 2(FR2) that may include frequency bands from 24.25 GHz to 52.6 GHz) mayimply that the propagation characteristics of the channel will influencethe system design. As frequencies increase, the channel may experiencehigher path losses and more abrupt changes. In high frequency bands,large-scale antenna arrays may be used to achieve high beamforming gainso as to compensate for the high propagation loss. The resultingcoupling loss may be kept at high level to support the desired datathroughput or coverage. The use of directional beam based communicationmay need accurate beam pairing, and the correct beam direction should beassociated with the channel, for example in terms of angle of arrivaland angle of departure in azimuth and/or elevation. The correct beamdirection may be dynamically adjusted with the channel change.

The following example downlink (DL) and uplink (UL) beam managementprocedures, including P-1, P-2, P-3, U-1, U-2, and U-3 proceduresdescribed below, may be considered for NR systems. A P-1 procedure maybe used to enable WTRU measurement on different transmission receptionpoint (TRP) transmission (Tx) beams to support selection of TRP Tx beamsand WTRU reception (Rx) beam(s). The beamforming procedure at the TRPmay include an intra/inter-TRP Tx beam sweep from a set of differentbeams. The beamforming procedure at a WTRU may include a WTRU Rx beamsweep from a set of different beams. A TRP Tx beam and a WTRU Rx beammay be determined jointly or sequentially. A P-2 procedure may be usedto enable WTRU measurement on different TRP Tx beams to possibly changeinter/intra-TRP Tx beam(s). For example, the change in inter/intra-TRPTx beam(s) may be from a different (e.g., smaller) set of beams for beamrefinement than in P-1. In an example, the P-2 procedure may be aspecial case of the P-1 procedure. A P-3 procedure may be used to enableWTRU measurement on the same TRP Tx beam to change the WTRU Rx beam inthe case that the WTRU uses beamforming. A U-1 procedure may be used toenable TRP measurement on different WTRU Tx beams to support selectionof WTRU Tx beams and/or TRP Rx beam(s). A U-2 procedure may be used toenable TRP measurement on different TRP Rx beams to possiblychange/select inter/intra-TRP Rx beam(s). A U-3 procedure may be used toenable TRP measurement on the same TRP Rx beam to change the WTRU Txbeam in the case that the WTRU uses beamforming.

A bandwidth part (BWP) may indicate a contiguous set of physicalresource blocks selected from a contiguous subset of the common resourceblocks for a given numerology (u) on a given carrier in NR. For example,in the DL, a WTRU may be configured with up to four BWPs, such that onecarrier BWP may be active at a given time (i.e., active DL BWP) from aWTRU perspective. The WTRU may not be expected to receive for examplephysical downlink shared channel (PDSCH), physical downlink controlchannel (PDCCH), channel state information reference signal (CSI-RS),and/or tracking reference signal (TRS) outside of an active BWP. In theUL, a WTRU may be configured with up to four carrier BWPs, and onecarrier BWP may be active at a given time. If a WTRU is configured witha supplementary UL channel, the WTRU may be configured with up to anadditional four carrier BWPs in the supplementary UL channel. Onecarrier BWP may be active at a given time (i.e., active UL BWP) from aWTRU perspective. For example, the WTRU may not transmit physical uplinkshared channel (PUSCH) or physical uplink control channel (PUCCH)outside an active BWP.

For each BWP, any one or more of the following parameters may beconfigured (e.g., sent to the WTRU) for control resource sets (CORESETs)for all types of search space(s) (SS) for DL BWPs in a primary cell(Pcell): BWP indicator field in DCI format 1_1, which may indicate anactive DL BWP; BWP indicator field in DCI format 0_1, which may indicatean active UL BWP; for the Pcell, higher layer parameter Default-DL-BWP,which may indicate a default DL BWP among configured DL BWPs (if a WTRUis not provided a default DL BWP parameter via higher layer, the defaultBWP may be the initial active DL BWP); and/or. A sounding referencesignal (SRS) may be transmitted within a BWP even when frequency hoppingis activated.

Release 15 (R15) NR MIMO features offer foundation for further potentialenhancements in Release 16 (R16) NR. For example, although Type II CSIspecified in R15 may offer large gain over advanced CSI Release 14 (R14)LTE, there may be a performance gap from near-ideal CSI, for example inthe case of multi-user (MU)-MIMO. R15 NR MIMO may accommodatemulti-TRP/panel operation, and may be used for standard-transparenttransmission operations and small numbers of TRPs/panels. Althoughspecification support for multi-beam operation has been specified in R15NR (e.g., targeting over-6 GHz frequency band operation), some aspectssuch as beam failure recovery and enabling schemes for DL/UL beamselection may be basic and may be improved upon for increasedrobustness, lower overhead, and/or lower latency. Moreover, there is aneed for enhancement to multi-beam operation to allow full powertransmission in the case of UL transmission with multiple poweramplifiers.

NR MIMO enhancements may be directed to multi-beam operations and mayinclude enhancements to multi-TRP/panel transmission to improvereliability and robustness with ideal and/or non-ideal backhaul. Forexample, DL control signaling may be specified for efficient support ofnon-coherent joint transmission. In another example, UL controlsignaling and/or reference signal(s) may be designed for non-coherentjoint transmission. Other enhancements to multi-beam operation, forexample targeting frequency range FR2 (24250 MHz-52600 MHz), mayinclude: UL and/or DL transmit beam selection to reduce latency andoverhead; UL transmit beam selection for multi-panel operation thatfacilitates panel-specific beam selection; beam failure recovery forsecondary cell (Scell) based on the beam failure recovery; and/ormeasurement and reporting of either layer 1 reference signal receivedquality (L1-RSRQ) or layer 1 signal-to-interference-plus-noise ratio(L1-SINR).

For an efficient UL transmit beam selection for multi-panel operationthat facilitates panel-specific beam selection, a WTRU may provideinformation to a gNB to assist UL beam management. Assistant orassistance information may be defined, for example in the case where amulti-panel WTRU may be associated with multiple panels from the sameTRP or different TRPs. Based on the WTRU assistance information,efficient SRS configuration may facilitate panel-specific beammeasurement and selection. For example, the WTRU assistance informationmay indicate which SRS resources/sets should be transmitted on whichWTRU panel and/or when SRS resources/sets should be transmitted. Inanother example, the number of resources that should be used fortransmission from each WTRU panel at a certain time instance may bedetermined.

Efficient SRS triggering and transmissions may be supported with reducedlatency to solve dynamic beam quality degradation in various cases suchas WTRU mobility, rotations and/or beam blockages. A mapping may bedefined between one or more triggered SRS resource sets and one or moreWTRU panels. The number of SRS resources in each set and the number ofSRS resource sets may match the capability of different WTRU panels.

For efficient DL transmit beam selection with reduced latency andoverhead, measurement and reporting configuration may consider differentDL transmit schemes such as non-coherent joint transmission, coherentjoint transmission and/or dynamic point selection (DPS). For example,the configured resource setting may differentiate the beams fromdifferent TRPs and different TRP panels with controlled configurationoverhead. The measurement and reporting setting may consider beamtraining latency, resource transmission overhead at the network andmeasurement overhead at the WTRU in the case of large numbers of beamsfrom multiple TRPs and TRP panels. A WTRU may support differential beamreporting and group based beam reporting more efficiently in the case ofmulti-TRP/panel.

Mechanisms for low latency and efficient beam management are describedherein for different scenarios, such as any of the following examplescenarios: UL and DL beam sweeping and/or selection procedures formulti-TRP/panel transmission; DL beam measurement and reportingconfiguration for multi-TRP/panel transmission; DL beam measurementreporting procedure for multi-TRP/panel transmission; and/or DL and ULbeam indication for multi-TRP/panel transmission.

Methods and configurations may be defined for UL beam management formulti-TRP/panel transmission. In the following examples, the referencesignal for UL beam management may be SRS, however any other referencesignals may be used to replace or complement the use of SRS. UL beammanagement for multi-TRP/panel transmission may include WTRU capabilityreporting and/or SRS configuration.

During a WTRU capability reporting procedure, a WTRU with multipleantenna panels may provide assistance information to the network (e.g.,gNB/TRP) for panel specific UL beam management. The assistanceinformation may include, but is not limited to include, any of thefollowing example WTRU capability parameters: NumberOfAntennaPanel;maxNumberSimultaneousAntennaPanel-PerCC; AntennaPanelStructure; and/oruplinkBeamManagement. A NumberOfAntennaPanel information element (IE)may refer to a total number of antenna panels physically supported bythe WTRU. A maxNumberSimultaneousAntennaPanel-PerCC IE may refer to anumber of antenna panels that may be used (e.g., for UL transmission(TX) and/or DL reception (RX)) by the WTRU in one OFDM symbol(simultaneously) per each component carrier (CC). AnAntennaPanelStructure IE may refer to whether the WTRU contains onlydirectional antenna panel(s) or a combination of omni-directionalantenna panel(s) and directional antenna panels. AnAntennaPanelStructure IE may indicate or define whether the WTRUcontains homogenous or heterogeneous antenna panels. For example, theAntennaPanelStructure IE may indicate the maximum number of supported ULTX beams by each panel may be the same or different. In another example,the AntennaPanelStructure IE may indicate the maximum number of SRSresources that may be configured for the WTRU per CC or per BWP. Anantenna panel may be an antenna group including multiple beams orantenna ports. The antenna panel may be a physical WTRU panel or a WTRUantenna group or antenna port(s) group. Different antenna panels maycontrol its Tx beam, transmission power and/or transmission timingindependently. Herein, antenna panel and panel are used interchangeably.

An uplinkBeamManagement IE may define support of beam management for UL.The capability may include indications of any of the following exampleparameters: maximum directional coverage, where for example each panelthat is associated with one or more beams may cover a certain degree ofcoverage by one or each antenna panel; maximum overlapped directionalcoverage, where for example adjacent antenna panels may have certaindegree of overlapped radio access coverage by two adjacent antennapanels; maximum number of SRS resource sets supported by one or eachantenna panel; maximum number of SRS resources per SRS resource set;maximum number of antenna panels that may be utilized simultaneously,which may be for example the number of antenna panels that may performUL TX beam sweeping simultaneously. The uplinkBeamManagement IE mayinclude a list of antenna panel specific entries, such that each entrymay include any of the following example parameters: antenna panelidentification defining the differentiation of different antenna panelsand entries; directional coverage defining spatial relative directionsof this antenna panel; maximum number of SRS resource sets supported bythis panel; maximum number of SRS resources per SRS resource setsupported by this panel; and/or a maximum number of beams swept by thispanel.

In an example, a multi-panel WTRU may be equipped with homogenousantenna panels, where each antenna panel may have similar capabilitiesfor UL TX beam (e.g., the same number of supported beams and/or the samemagnitude of directional coverage). An example of SRS configuration(e.g., SRS-Config IE) for a multi-panel WTRU equipped with homogenousantenna is shown in Table 2. The WTRU may be configured with one ormultiple SRS resource sets.

For each configured SRS resource set, when the parametersrs-AntennaPanelID (e.g., The ID of the WTRU antenna panel associatedwith a SRS resource set) is not configured, the SRS resource set may notbe associated with a specific WTRU antenna panel. When the UL beamsweeping is performed, for example, the WTRU may transmit the SRSresources of a SRS resource set over different beams (e.g., U3) or overthe same beam (e.g., U2), the SRS resources of the same SRS resource setare transmitted from different WTRU antenna panels. Separate UL beamsweeping among different WTRU antenna panels may be supported in thiscase, where the UL beam sweeping at the WTRU may be performedseparately/sequentially by different WTRU antenna panels. This approachmay incur small overhead of SRS configurations since the configured SRSresource sets are shared by different WTRU antenna panels. FIG. 3 showsa signaling diagram of an example beam sweeping procedure 300 includingseparate and sequential (in time) UL TX beam sweeping at the WTRU 304among different WTRU antenna panels 321 and 322. The network, forexample gNB/TRP 302, may send SRS configuration 306 to the multi-panelWTRU 304 to configure the WTRU 304 with at least one SRS resource set.The WTRU 304 may perform beam sweeping 310 and 315 one at a time(sequentially) on each antenna panel 321 and 322 using the same SRSresource set (i.e., transmit SRS in the UL on each of the beams of therespective antenna panels 321 and 322).

While the WTRU 304 performs the UL beam sweeping 310 and 316, the linkbetween other antenna panels of the WTRU 302 and associated gNBs/TRPs(not shown) may remain active and the WTRU 304 may continue data and/orcontrol signaling communications with other gNBs/TRPs. Because the sameSRS resource set may be shared and transmitted by multiple WTRU panels,neighboring TRPs may be made aware of which of the multiple WTRU panels321 and 322 is transmitting on the configured SRS resource set at agiven time.

In an example, the WTRU 304 may be configured with an SRS transmissiongap, where the slot offset and the WTRU panel ID or order are predefinedby the network. When the neighboring TRPs are signaled (e.g. radioresource control (RRC) signaling) to measure the SRS transmissions frommulti-panel WTRU 304, the neighboring TRPs may also receive the SRStransmission gap information. For example, as shown in FIG. 3 , duringthe first round of beam sweeping 310 during a first time period (e.g.,one or more symbols, one or more slots) the WTRU 304 performs beamsweeping at antenna panel 321 and the neighboring TRPs perform UL beammeasurement 308 (e.g., from the beam sweeps 321 and 322), and during thesecond round of beam sweeping 316 the WTRU 304 performs beam sweeping atantenna panel 322 and the neighboring TRPs perform UL beam measurement314. In another example not shown, the WTRU 304 or a TRP in the network(e.g., a primary TRP or default TRP) may send explicit signaling toother neighboring TRPs with the WTRU panel ID for the WTRU 304 andindication of a slot offset for the next transmission of partial or allSRS resources configured within the SRS resource set. Each SRS resource(time/frequency domain position) may correspond to a specific WTRU 304TX beam (beam 1, 2, 3, 4 on panel 321 and 322) such that transmission ofan SRS resource may be mapped to a specific beam. When an SRS resourceis measured by the gNB/TRP 302 after a beam sweeping transmission, thegNB/TRP 302 may know which WTRU 302 beam is used. Based on the UL beamsweeping 310 and 312, the gNB/TRP 302 may select and assign UL TX beamsto the WTRU 304 using UL beam indication frames 312 and 318,respectively.

Due to the share of configured SRS resources sets, the overall timeduration of beam training may be large if the number of WTRU antennapanels and the SRS transmissions from each panel that needs to betrained are large. For example, for certain beam management procedures(e.g., a U1 beam management procedure) global beam sweeping may besupported. In another example, local beam sweeping may be supported,where a subset of beams of one panel or a subset of the overall WTRUpanels may be refined, and the overall time cost may not be significant.

In an example, a multi-panel WTRU may perform separate/sequential UL TXbeam sweeping for the SRS resource set(s) or/and SRS resources that havea higher layer parameter resourceType set to ‘periodic’ and/or‘semi-persistent’. In this case, sweeping delay may be tolerable and theoverhead of SRS configurations may be significant in terms of long-termcost. In another example, the number of configured SRS resource sets maybe the same as the number of WTRU antenna panels, and in this case theparameter srs-AntennaPanelID may not need to be configured. In otherwords, the index of each configured SRS resource set may implicitlyrepresent the WTRU panel index.

For each configured SRS resource set, when the parametersrs-AntennaPanelID is configured, the SRS resource set may be associatedwith a specific WTRU antenna panel. When the WTRU performs UL beamsweeping, the SRS resources from different SRS resource sets may betransmitted only from the specifically associated WTRU antenna panels.Joint UL beam sweeping among different WTRU antenna panels may besupported in this case, where the UL beam sweeping at the WTRU may beperformed jointly/simultaneously by different WTRU antenna panels. FIG.4 shows a signaling diagram of an example beam sweeping procedure 400including joint/simultaneous (in time) UL TX beam sweeping at the WTRU404 among different WTRU antenna panels 421 and 422. The network, forexample gNB/TRP 402, may send SRS configuration 406 to the multi-panelWTRU 404 to configure the WTRU 404 with SRS resource sets. The WTRU 304may perform beam sweeping 410 simultaneously on antenna panels 421 and422 using different SRS resource set. In this case, the overhead of SRSconfiguration 406 may be higher than the sequential beam sweeping casebecause the configuration of SRS resource sets is panel specific andeach WTRU 404 antenna panel 421 and 422 may be configured with one ormultiple SRS resource sets. While the WTRU 404 performs the UL beamsweeping 410 simultaneously from multiple WTRU antenna panels 421 and422 at the same a time, the links between the WTRU 404 antenna panels421 and 422 performing UL beam sweeping 410, and associated TRPs/gNB maybe affected, which means the data or control signaling communications ofthe WTRU 404 with the associated TRPs/gNB are interrupted.

The time to perform joint beam sweeping among different WTRU antennapanels may be less than the time to perform sequential beam sweeping,resulting in lower latency due to UL beam managements. In an example, amulti-panel WTRU may perform joint/simultaneous UL TX beam sweeping forthe SRS resource set(s) or/and SRS resources that have the higher layerparameter resourceType set to ‘aperiodic’ or/and ‘semi-persistent’. Inthis case, the configuration overhead of SRS resources may be tolerabledue to one-time (‘aperiodic’) or short-term (semi-persistent) cost andthe beam sweeping delay is more important and joint/simultaneous beamsweeping is accelerated.

In an example, panel specific configuration may be achieved withoutexplicitly configuring parameters using a panel ID. For example, inorder to differentiate the resources configured for each antenna panel,a group ID or pool ID may be used to realize the panel specificconfiguration. In this case, the example configuration shown in Table 2may be modified to not include the AntennaPanelID explicitly, and toinclude a group ID or pool ID (or other similar IDs).

TABLE 2 Example SRS-Config IE for a multi-panel WTRU equipped withheterogeneous antenna panels -- ASN1START -- TAG-SRS-CONFIG-STARTSRS-Config ::= SEQUENCE { ... srs-ResourceSetToAddModList SEQUENCE(SIZE(1.. maxNrofSRS-ResourceSets)) OF SRS- ResourceSet OPTIONAL, --Need N ... AntennaPanelIDlist SEQUENCE(SIZE(1..maxNrofSRS-AntennaPanels)) OF AntennaPanelIDsrs-ResourceSetToAddModList ::= SEQUENCE (SIZE(1..maxNrofSRS-AntennaPanels)){ AntennaPanelID SEQUENCE (SIZE(1..maxNrofSRS-ResourceSetsPerPanel)) OF SRS-ResourceSet OPTIONAL, -- Need MAntennaPanelID SEQUENCE (SIZE(1.. maxNrofSRS-ResourceSetsPerPanel)) OFSRS-ResourceSet OPTIONAL, -- Need M ... } ... } SRS-ResourceSet ::=SEQUENCE { ... srs-AntennaPanelID AntennaPanelID  OPTIONAL, ... } --TAG-SRS-CONFIG-STOP -- ASN1STOP

In another example, a multi-panel WTRU may be equipped withheterogeneous antenna panels, such that each antenna panel may havedifferent capabilities for UL TX beam (e.g., different number ofsupported beams, different magnitude of directional coverage). Anexample of SRS configuration (e.g., SRS-Config IE) for a multi-panelWTRU in this case is shown in Table 3. In this case, the WTRU may beconfigured with one or multiple SRS resource sets, and each SRS resourceset may have different numbers of SRS resources to match the differentnumber of beams on each WTRU antenna panel.

TABLE 3 Example SRS-Config IE for a multi-panel WTRU equipped withheterogeneous antenna panels -- ASN1START -- TAG-SRS-CONFIG-STARTSRS-Config ::= SEQUENCE { ... srs-ResourceSetToAddModList SEQUENCE(SIZE(1..maxNrofSRS-ResourceSets)) OF SRS- ResourceSet OPTIONAL,  --Need N ... AntennaPanelIDlist SEQUENCE(SIZE(1..maxNrofSRS-AntennaPanels)) OF AntennaPanelIDsrs-ResourceSetToAddModList ::= SEQUENCE(SIZE(1..maxNrofSRS-AntennaPanels)) { AntennaPanelID SEQUENCE (SIZE(1..maxNrofSRS-ResourceSetsPerPanel)) OF SRS-ResourceSet OPTIONAL, -- Need MAntennaPanelID SEQUENCE (SIZE(1.. maxNrofSRS-ResourceSetsPerPanel)) OFSRS-ResourceSet OPTIONAL, -- Need M ... } ... } SRS-ResourceSet ::=SEQUENCE { ... srs-AntennaPanelID AntennaPanelID  OPTIONAL, ... } --TAG-SRS-CONFIG-STOP -- ASN1STOP

In an example, when a WTRU provides assistant (or assistance)information to the network (gNB/TRP) to assist UL beam management, WTRUcapability information (e.g., any of the capability parameters describedherein) may be transmitted in the WTRU capability reporting. In anotherexample, WTRU capability information may be transmitted in other ways,for example by RRC signaling, implicit request, explicit request or WTRUinitiated reporting. For example, a WTRU may include at least a subsetof capability parameters (e.g., minimum WTRU capability parameters) inWTRU capability reporting in order to reduce the reporting overhead, andthe WTRU may send the remaining capability parameters in subsequentmessages (e.g., RRC signaling, medium access control element (MAC-CE),L1 messages), for example when the network requests the remainingcapability parameters. In another example, for the purpose energypreservation or other factors such as privacy, a WTRU may report lowercapability (e.g., report and use a lower number of panels than theactual number of antenna panels at the WTRU) or dynamically switchbetween high performance mode or low performance mode and dynamicallysend different capability parameters (or only the changes to thecapability parameters) to the network.

Methods for SRS triggering and SRS transmissions are described herein.In the following examples, a multi-panel WTRU may be configured with oneor more SRS resource configuration(s). Example WTRU configurations ofSRS resource sets to support SRS triggering for a multi-panel WTRU aregiven in Table 4. With reference to the example configurations in Table4, any of the following example actions may occur when the higher layerparameter resource Type in SRS-Resource and/or SRS-ResourceSet (e.g., asin Table 2) is set to ‘aperiodic’ (i.e., when the SRS resource sets arenot configured for periodic use). In a first example action, the WTRUmay receive a DCI (e.g., a downlink DCI, a group common DCI, or anuplink DCI based command) such that a codepoint of the DCI may triggerone or more SRS resource set(s) to be used for SRS transmission. In anexample, a multi-panel WTRU may be configured with three SRS resourcesets, and each resource set may have a corresponding resource set ID(e.g., srs-ResourceSetID 2, srs-ResourceSetID 3 and srs-ResourceSetID4). In an example, the SRS resource sets with srs-ResourceSetIDs 2 and 3may be configured with the higher layer parameteraperiodicSRS-ResourceTrigger set to 1. Table 5 shows an example 2-bitDCI SRS request field values to trigger one or multiple SRS resourcesets for a multi-panel WTRU.

With reference to Tables 4 and 5, in the case that the WTRU receives aDCI with a DCI field for triggering SRS resource sets (e.g., a 2-bit or3-bit SRS request field for triggering one or more SRS resource set(s))set to ‘01’, then SRS resource set(s) configured with higher layerparameter aperiodicSRS-Resource Trigger set to ‘1’ are triggered, and inthis example two SRS resource sets (srs-ResourceSetIDs 2 and 3) aretriggered to be used for SRS transmission in appropriate symbol(s) andslots (e.g., as indicated by slot offset or symbol offset). In the casethat the WTRU receives a triggering DCI for triggering SRS resource setswith value ‘10’ (or 2), then SRS resource set(s) configured with higherlayer parameter aperiodicSRS-Resource Trigger set to 2 are triggered,and in this example one SRS resource set (srs-ResourceSetIDs ID 4) istriggered to be to be used for SRS transmission. In the case that twoSRS resource sets are triggered for use for SRS transmission, the WTRUmay perform UL beam sweeping from two WTRU antenna panels. In the casethat one SRS resource set is triggered, the WTRU may perform UL beamsweeping from one WTRU antenna panel. If the triggering DCI contains aDCI field indicating specific WTRU panel(s), the indicated WTRU antennapanel may override the high layer parameter srs-AntennaPanelIDconfigured for the triggered SRS resource set(s) in the SRSconfiguration IE. If the triggered SRS resource set(s) are configuredwith srs-AntennaPanelID in the SRS configuration, the WTRU may transmitthe triggered SRS resource sets from the associated WTRU antenna panelsin a future slot. For example, the future time slot may be determinedbased on the high layer parameter slotOffset.

If the triggered SRS resource set(s) are not configured withsrs-AntennaPanelID in the SRS configuration, the WTRU may transmit thetriggered SRS sets by following default rules or by using pre-definedWTRU antenna panels. Any of the following example rules may be used by aWTRU to select a WTRU antenna panel for the transmission on triggeredSRS resource set(s) (e.g., in the case that srs-AntennaPanelID was notconfigured). In an example rule, the WTRU may select from the set ofcurrently active WTRU antenna panels with on-going signals or datatransmissions. In some cases, not all antenna panels on a WTRU may beactive at all times, for example for interference reduction or powersaving. In another example rule, the WTRU may select from the set ofWTRU panel(s) with link(s) quality (e.g., layer one reference signalreceived power (L1-RSRP), L1-RSRQ, block error rate (BLER)) below (orabove) a pre-determined threshold. In another example rule, the WTRU mayselect from the set of WTRU panel(s) with beams transmitting signalingmessages/data on one or multiple default BWP(s) or CC(s). In anotherexample rule, the WTRU may select from the set of WTRU panel(s) withbeams within a certain (e.g., pre-determined) directional coverage. Inanother example rule, the WTRU may select from the set of WTRU panel(s)that are explicitly or implicitly requested by the network (gNB or TRP).For example, when the quality of a link between a WTRU panel and a TRPdrops (which may be determined based on a TRP L1-RSRP measurement), theTRP may explicitly (e.g., send a triggering DCI including the antennapanel ID of WTRU panels) and/or implicitly (e.g., send a triggering DCIindicating SRS resource set(s) that have high layer parametersrs-AntennaPanelID configured) request the WTRU to perform an UL TX orRX beam sweeping from a subset of the implicitly or explicitly indicatedWTRU panels.

In some cases, the number of the triggered SRS resource sets may be lessthan or equal to the number of WTRU antenna panels, which may bedetermined (e.g., based on rules defined herein) to perform UL beamtraining (e.g., using a U2 or U3 beam management procedure), thetriggered SRS resource sets may be transmitted using any one or more ofthe following example methods. In an example, if the triggering DCIcontains DCI field(s) indicating WTRU antenna panels, the SRS resourcesof the triggered SRS resource set(s) may be transmitted from the WTRUpanels indicated by the DCI field(s), which may override the WTRU panelsindicated by the high layer parameter srs-AntennaPanelID of eachtriggered SRS resource set. If no DCI fields indicate WTRU antennapanels, for the triggered SRS resource set(s) configured withsrs-AntennaPanelID(s), the SRS resources of the triggered SRS resourceset(s) may be used for transmitting SRS from the WTRU panels indicatedby the srs-AntennaPanelID(s).

If the triggered SRS resource set(s) is not configured withsrs-AntennaPanelID and no DCI field in the triggering DCI indicates WTRUantenna panel(s), then SRS resource availability may be considered. Forexample, if only one SRS resource in each of triggered SRS resource setmay be may be used for transmission at a given time instant, then at thegiven time instant, the WTRU may transmit in the triggered SRS resourceset(s) from the same number of WTRU panels (e.g., simultaneously as inFIG. 4 or sequentially as in FIG. 3 ). If the number of triggered SRSsets is less than the number of WTRU panels that need to perform UL beamtraining, some of the triggered SRS sets may be shared by more than oneWTRU panels. In this case, the neighboring TRPs may be informed of theWTRU panel ID(s) at the time each shared SRS resource set is transmitted(e.g., as shown in FIG. 3 ). For example, the WTRU may be configuredwith an SRS transmission gap known to the network in advance. In anotherexample, the network may receive explicit notifications of the WTRUpanel(s) to be used for beam sweeping before each shared SRS resourceset is transmitted.

TABLE 4 Example WTRU configurations of SRS resource sets to support SRStriggering for a multi-panel WTRU -- ASN1START -- TAG-SRS-CONFIG-START... SRS-ResourceSet ::= SEQUENCE { srs-ResourceSetId 2, ...srs-AntennaPanelID AntennaPanelID OPTIONAL, resourceType CHOICE {aperiodic SEQUENCE { aperiodicSRS-ResourceTrigger 1, ... }, ... } ... }SRS-ResourceSet ::= SEQUENCE { srs-ResourceSetId 3, ...srs-AntennaPanelID AntennaPanelID OPTIONAL, resourceType CHOICE {aperiodic SEQUENCE { aperiodicSRS-ResourceTrigger 1, ... }, ... } ... }SRS-ResourceSet ::= SEQUENCE { srs-ResourceSetId 4, ...srs-AntennaPanelID AntennaPanelID OPTIONAL, resourceType CHOICE {aperiodic SEQUENCE { aperiodicSRS-ResourceTrigger 2, ... }, ... } ... }... -- TAG-SRS-CONFIG-STOP -- ASN1STOP

TABLE 5 Example 2-bit DCI SRS request field to trigger one or more SRSresource sets for a multi-panel WTRU Value of the DCI Single panel ormulti-panel SRS field Triggered aperiodic SRS resource set(s)transmissions 00 No aperiodic SRS resource set triggered N/A 01 SRSresource set(s) configured with SRS resource set 2 and set 3 are higherlayer parameter aperiodicSRS- transmitted from 2 WTRU antennaResourceTrigger set to 1 panels 10 SRS resource set(s) configured withSRS resource set 4 is transmitted higher layer parameter aperiodicSRS-from 1 WTRU antenna panel ResourceTrigger set to 2 11 SRS resourceset(s) configured with higher layer parameter aperiodicSRS-ResourceTrigger set to 3

FIG. 5 is a flow diagram of an example beam sweeping mode selection andantenna panel association procedure 500 for multi-TRP based SRS (orreference signal (RS)) transmissions using SRS resources, which may bepart of an UL beam management procedure. At 502, the WTRU may send orreport antenna panel capability information (e.g., to the TRP/gNB). Theantenna panel capability information may indicate, for example, any ofthe following information: a number of WTRU antenna panels; antennapanel IDs identifying the antenna panels at the WTRU; and/or a number ofsupported beams for each antenna panel at the WTRU. At 504, the WTRU mayreceive (e.g., from the TRP/gNB) an SRS resource configuration forconfiguring SRS resources and/or associated antenna identifiers. The SRSresource configuration may indicate any of the following information:time/frequency (TF) location information of the configured SRS resourceset(s); associated antenna panel identifiers (IDs) identifying antennapanels at the WTRU for the configured SRS resource set(s); and/or beamsfor the configured SRS resource sets. At 506, the WTRU may receive(e.g., from the TRP/gNB) an SRS transmission trigger frame identifyingtriggered SRS resource sets from the set of configured SRS resource setsto be used for SRS transmission. The SRS transmission trigger mayindicate antenna IDs of antenna panels at the WTRU to be used with thetriggered SRS resource sets. The identified antenna panels may overridepreviously signaled antenna panel associations at the WTRU (e.g.,previous antenna panel associations in the SRS resource configuration).Thus, the WTRU may identify the antenna panels to be used with thetriggered RS resource sets based on the SRS configuration and/or the RStransmission trigger information (with or without override). FIG. 6shows a frame format of an example DCI frame 600 that may be used as anSRS transmission trigger frame including a WTRU antenna panel field 601(which may be in the form of a list) and an SRS resource set triggeringfield 602 (which may be in the form of a list) for UL beam sweeping. Notall fields of the DCI frame 600 are shown.

With reference to FIG. 5 , at 507, the WTRU may determine an UL TX beamsweeping mode based on the triggered SRS resource sets and theidentified antenna panels, for example according to the exampleprocedure given in steps 508-512. At 508, the WTRU may compare thenumber of triggered SRS resource sets to the number of identifiedantenna panels. If the number of triggered SRS resource sets is lessthan the number of identified antenna panels, then the WTRU may use asequential UL TX beam sweeping mode (e.g., as shown in FIG. 3 or FIG. 7). If the number of triggered SRS resource sets is equal to (or morethan) the number of identified antenna panels, then the WTRU may use asequential UL TX beam sweeping mode (e.g., as shown in FIG. 3 or FIG. 7) or a simultaneous UL TX beam sweeping mode (e.g., as shown in FIG. 4or FIG. 7 ). In another example, the WTRU may determine an UL TX beamsweeping mode based on explicit signaling received from the gNB/TRP.

At 514, the WTRU may determine an association between the triggered RSresources sets and the set of antenna panels. For example, theassociation may be determined based on implicit indication of antennapanel ID from SRS resource set ID(s) or implicit indication of antennapanel ID from beam ID(s). In another example, the association may bedetermined based on explicitly indicated antenna panel ID(s) in theresource set configuration. In another example, the association may bedetermined based on dynamic signaling (e.g., from the gNB/TRP)explicitly indicating antenna panel ID(s). At 516, the WTRU may performUL beam sweeping using the triggered RS resource sets and the set ofantenna panels according to the association between the triggered RSresources sets and the set of antenna panels. At 518, the WTRU mayreceive (e.g., from the gNB/TRP) an RS resource indicator (SRI) formulti-panel UL physical uplink shared channel (PUSCH) transmission totransmit uplink data using multiple antenna panels from the plurality ofantenna panels. For example, the SRI may have been determined by the TRPbased on the UL beam sweeping using the triggered RS resource sets andthe set of antenna panels.

FIG. 7 shows a signaling diagram of an example beam sweeping procedure700 including simultaneous and sequential UL TX beam sweeping at theWTRU 704 among different WTRU antenna panels 721, 722, 723. In theexample beam sweeping procedure 700, the WTRU 704 may have three antennapanels 721, 722, 723 to communicate with multiple TRPs 701 and 702 andmay have two triggered SRS resource sets 731 and 732 that can be usedsimultaneously. During a first time period, the WTRU 704 may performbeam sweeping using SRS resource set 731 on antenna panel 721 at thesame time (simultaneously) the WTRU 704 performs beam sweeping using SRSresource set 733 on antenna panel 722. In a next time period and thussequentially, the WTRU 704 may perform beam sweeping using SRS resourceset 731 on antenna panel 723.

If more than one SRS resource in each of triggered SRS resource set maybe used for transmission at a given time, then at the given time theWTRU may transmit the triggered SRS resource set(s) from the same orlarger number of WTRU panels simultaneously (e.g., FIG. 4 or FIG. 7 ) orsequentially (e.g., FIG. 3 or FIG. 7 ).

FIG. 8 shows a signaling diagram of an example beam sweeping procedure800 including simultaneous UL TX beam sweeping at the WTRU 804 amongdifferent WTRU antenna panels using different SRS resources within aset. In the example beam sweeping procedure 800, the WTRU 804 may havethree antenna panels 821, 822, 823 to communicate with multiple TRPs 801and 802 and may have two triggered SRS resource sets 831 and 832 thatcan be used simultaneously. In the example beam sweeping procedure 800,two SRS resource sets 831 and 832 are triggered, and the WTRU 804transmits on SRS set 831 using the WTRU antenna panels 821 and 822simultaneously during the same time period. However, due to the limitednumber of SRS resources in the SRS resource set 831, WTRU 804 mayperform local beam sweeping (e.g., sweeping beams 3 and 4 at panel 821,and sweeping beams 1 and 2 at the panel 822) on antenna panels 821 and822, while simultaneously the WTRU performs a beam sweep on the SRSresource set 832 using WTRU antenna panels 823 using all beams (e.g.,beams 1, 2, 3, 4 at panel 723).

Once a configured SRS resource set(s) is determined/triggered for theSRS transmissions from a specific panel (e.g., associated with theantenna panel), the WTRU may determine the beam(s) to be used for eachSRS resource within the triggered SRS resource set(s). In an example, ahigher layer parameter spatialRelationInfo may contain a DL RS ID,(e.g., CSI-RS Resource Indicator (CRI), SS/PBCH Resource Block Indicator(SSBRI), the ID of a reference ‘ssb-Index’ or ‘csi-RS-Index’) or UL RSID (e.g., SRS, the ID of a reference “srs”), which may be used toconfigure each SRS resource and indicate the beam (e.g., spatial domaintransmission filter) to be used by each SRS resource in the triggeredSRS resource set(s).

In single-panel case where a single antenna panel is associated with thetriggered SRS resources sets, the DL RS ID may uniquely represent a DLTX beam for a specific TRP/gNB, and the SRS ID may uniquely represent aUL TX beam for the WTRU.

In multi-panel case where a multiple antenna panels are associated withthe triggered SRS resources sets, if the RS ID is defined locally withinan antenna panel, there may be an ambiguity that a WTRU may not be ableto identify the indicated beam if multiple panels use a local beam IDspace (e.g., the IDs used for identifying beams may be the same ondifferent antenna panels). For example, for DL RS ID, if two panels of aTRP transmit WTRU specific CSI-RS resources simultaneously, and two DLTX beams (one beam from each panel of the TRP) may have the same CRI,such as CRI #3. When CRI #3 is configured to spatialRelationInfo for aSRS resource at a later time, the WTRU may not identify which DL TX beamis indicated by the CRI #3.

Any of the following example mechanisms may be used to resolve theambiguity of beam identity across different antenna panels. In anexample approach, an extended RS ID may be used. For DL RS ID, a WTRUmay be configured with multiple sets of CSI-RS resources, and/or a setof CSI-RS resources with multiple groups. In an example, a WTRU may beconfigured with multiple CSI-RS resource pools, where each resource poolincludes multiple resource sets. In another example, a WTRU may beconfigured with multiple resource settings, and each resource set maybeassociated with one TRP/gNB panel. In another example, synchronizationsignal block (SSB) resources may be grouped in multiple sets, where eachgroup is transmitted from one TRP/gNB panel. When a CSI-RS resource orSSB resource is measured by a WTRU, the RS ID for CSI-RS resource or SSBresource may be differentiable by group ID, set ID or pool ID. Forexample, an DL RS ID include several segments/parts, and onesegment/part may represent the group ID or set ID or pool ID, andanother segment/part may represent the RS ID within a group, a set or apool.

Similarly, the UL RS ID may be defined. When WTRU specific SRS resourcesare configured, there may be multiple SRS resource groups or sets orpools configured. The SRS ID (e.g., SRI) of each group or set or poolmay contain several segments/parts as well. One segment/part mayrepresent the group ID or set ID or pool ID, and another segment/partmay represent the RS ID within a group, a set or a pool.

In another example approach to resolve the ambiguity of beam identityacross different antenna panels, an RS ID may be associated with aspecific UL or DL panel. When a DL RS ID is indicated or configured, theDL RS ID may refer to the DL RS measured most recently on the associatedWTRU panel. For example, if two panels of a TRP transmit CSI-RSsimultaneously, two DL TX beam may be indexed as a common name (e.g.,CRI #3). If the two DL TX beams with the same name (e.g., CRI #3) aremeasured by the same WTRU panel, the two DL beams are determined to bewith respect to the same RX beam at the WTRU. If beam correspondenceholds at the WTRU, there is no ambiguity and the WTRU may be able to usethe same DL RX beam as the UL TX beam to transmit on associated SRSresource(s) if its higher layer parameter spatialRelationInfo isconfigured with the common name (e.g., CRI #3). If the two DL TX beamswith the same name (e.g., CRI #3) are measured by different WTRU panels,then the name CRI #3 may indicate the DL TX beam measured by therespective WTRU panel. For example, if the WTRU needs to determine UL TXbeam of a SRS resource configured with CRI #3 (contained byspatialRelationInfo of this SRS resource) for a WTRU panel, the WTRU mayassume the CRI #3 indicates the DL TX beam most recently measured by thesame WTRU panel. If this WTRU panel does not measure any DL TX beam withthe name CRI #3, but configured with a SRS resource which contains CRI#3, the WTRU may just ignore this configured beam CRI #3 and considerthe high parameter spatialRelationInfo is not configured. Similarly,when a UL RS ID is indicated or configured for a SRS resource, such asSRI #4, this ID only refers to the beam index from the same WTRU panelwhere the SRS resource is configured to be transmitted. In an example,if an SRS resource ID 5 is configured to transmitted by a WTRU panel,the SRI #4 contained by the high parameter spatialRelationInfo of SRSresource with ID 5 may indicate the beam of the same WTRU panel thatmost recently transmitted the SRS resource with ID 4.

In another example approach to resolve the ambiguity of beam identityacross different antenna panels, a parameter (e.g., a panel ID, groupID, set ID, or any parameter to differentiate panel specificconfiguration for beamforming such as a group or set of beams) may beused to differentiate beam IDs from different TRP panels or WTRU panels.

DL beam management methods for multi-TRP/panel transmission aredescribed herein. In an example method, beam measurement and reportingmay be configured to reduce overhead and latency involved in beammeasurement and reporting configuration. In an example, DL beammeasurement and reporting for multi-TRP/panel transmissions may beconfigured by the gNB. In another example, a WTRU may request the amountof resources/sets for DL RSs (e.g., CSI-RS) for DL beam management.FIGS. 9A and 9B show network diagrams of example of beam pair linkrefinement 900A and 900B, respectively. In FIG. 9A, the rotation 912 ofthe WTRU 904 may cause beam pair links on WTRU panels 921 and 922 withTRPs 901 and 902, respectively, to be refined. In FIG. 9B, the beamblockage 914 between the WTRU 904 and TRP 902 may cause beam pair linkon WTRU panel 922 to be refined (and not on antenna 921). In beam pairlink refinement 900A and 900B, the amount of DL reference signalresources/sets needed may be different. Any of the following exampleprocedures may be used for a WTRU to indicate the amount of DL referencesignal resources/sets needed.

In an example of indicating the amount of DL reference signalresources/sets needed, the WTRU may perform capability reporting. Basedon reported WTRU capability parameters a WTRU may be configured with oneor multiple DL reference signal resources/sets. In an example, eachresource set may be associated with a TRP panel as shown in Table 6,where the high layer parameter indicates the ID of the associated withTRP panel. In another example, one resource set may includesubsets/groups of resources. Each group or subset of resources may beassociated with a TRP panel as shown in Table 7, where the high layerparameter indicates the ID of the associated TRP panel.

TABLE 6 Example DL RS resource set IE for multi-panel DL beam management-- ASN1START -- TAG-NZP-CSI-RS-RESOURCESET-START NZP-CSI-RS-ResourceSet::= SEQUENCE { nzp-CSI-ResourceSetId NZP-CSI-RS-ResourceSetId,nzp-CSI-ResourceSetPanelID TRP-AntennaPanelId, nzp-CSI-RS-ResourcesSEQUENCE (SIZE (1..maxNrofNZP-CSI-RS-Resources PerSet)) OFNZP-CSI-RS-ResourceId, ... } -- TAG-NZP-CSI-RS-RESOURCESET-STOP --ASN1STOP

TABLE 7 Example DL RS resource set IE for multi-panel DL beam management-- ASN1START -- TAG-NZP-CSI-RS-RESOURCESET-START NZP-CSI-RS-ResourceSet::= SEQUENCE { nzp-CSI-ResourceSetId NZP-CSI-RS-ResourceSetId,nzp-CSI-RS-Resources CHOICE { group0 SEQUENCE ( panelIDTRP-AntennaPanelId, resources SEQUENCE (SIZE(1..maxNrofNZP-CSI-RS-PerPanel)) OF NZP-CSI-RS-ResourceId }, group1SEQUENCE ( panelID TRP-AntennaPanelId, resources SEQUENCE (SIZE(1..maxNrofNZP-CSI-RS-PerPanel)) OF NZP-CSI-RS-ResourceId }, ... } ... }-- TAG-NZP-CSI-RS-RESOURCESET-STOP -- ASN1STOP

In another example, the WTRU may send an explicit request of a of DL RSresources/sets required for DL beam training. This explicit request maybe carried in a message (e.g., at L1, MAC-CE or RRC) or piggybacked on adata or control message. For example, the WTRU may transmit a list ofWTRU panels (e.g., one or multiple WTRU panel IDs) to the network, byassuming the network is aware of the required amount of DL RSresources/sets from a history request or WTRU capability reporting. Inanother example, the WTRU may send an implicit request of a of DL RSresources/sets required for DL beam training. Using an implicit request,the WTRU may transmit a value of DL RS AperiodicTriggerState to thenetwork. As a response, the network (TRP/gNB) may send back a triggeringDCI to trigger one or more aperiodic DL RS resource set(s) for beammeasurements.

With the assistance information from the WTRU, the WTRU may beconfigured by the gNB to perform more efficient DL beam measurement andreporting. For example, an efficient beam reporting periodicity for a P1beam management procedure may be configured to reduce latency. FIG. 10shows a signaling diagram of an example beam sweeping procedure 1000including appropriate configuration of reporting periodicity 1020 toreduce latency of beam training. As shown in FIG. 10 , an appropriatevalue of reporting periodicity 1020 may be configured for the WTRU 1004according to the assistance information (not shown) from the WTRU 1004and provided to the TRP 1001 in terms of the capability of related WTRU1004 antenna panels. The example beam sweeping procedure 1000 mayinclude the TRP 1001 providing the WTRU 1004 with DL RS configuration1006, the TRP 1001 performing beam sweeping 1010 on panels 1041 and 1042simultaneously in a first time period and the TRP 1001 performing beamsweeping repetitions 1016 on panels 1041 and 1042 simultaneously duringa second time period during the reporting periodicity 1020, and the WTRU1004 send the beam measurement reporting 1018 to the gNB based on the DLbeam sweeping.

In another example, an efficient beam reporting periodicity for a P1beam management procedure may be configured to reduce configurationoverhead. FIG. 11 shows a signaling diagram of an example beam sweepingprocedure 1100 including appropriate configuration of reportingperiodicity 1120 and 1122 to reduce configuration overhead of beamtraining. As shown in the FIG. 11 , the same set of DL RS resource isshared by both TRP 1101 panels 1141 and 1142 during appropriatereporting periodicity 1120 and 1122 to reduce the DL RS configuration1106 overhead. The WTRU 1104 may perform the independent beammeasurement reporting 1114 and 1119 after respective beam sweeping 1110and 1112 and beam sweeping 116 and 1118 completion on each respectiveTRP 1101 panel 1141 and 1142 (e.g., there is no ambiguity at the TRP1101).

In an example, a more efficient DL RX beam sweeping for a P3 and P1 beammanagement procedure may be configured. For P1, as shown in FIG. 10 andFIG. 11 , with the assistance information from the WTRU, the network(TRP/gNB) is able to configure the DL RS resources to be minimallyrepeated, such as only one repetition (e.g., the involved WTRU panel mayinclude only two DL RX beams, or WTRU may perform local RX beam sweepingon the involved WTRU so that only 2 RX beams are swept).

FIG. 12 shows a signaling diagram of an example DL RX beam sweepingprocedure 1200 at the WTRU 1204 by configuring an appropriate number ofCSI-RS resources. For a P3 procedure with the example DL RX beamsweeping procedure 1200, with the assistance information from the WTRU1204, the WTRU may be configured with an appropriate amount of DL RSresources (e.g., in DCI trigger 1206 triggering aperiodic DL RS) for theWTRU 1204 to sweep its RX beams on antenna panels 1231 and 1232. TheWTRU 1204 and the TRP 1201 may perform joint beam sweeping acrossmultiple WTRU panels 1231 and 1232 and TRP panels 1241 and 1242 (forexample, during fixed DL TX beam 1208). In an example not shown, theWTRU 1204 and TRP 1201 may perform sequential/separate beam sweepingacross multiple WTRU panels 1231 and 1232 and TRP panels 1241 and 1242.

To support Tx beam grouping, a TRP may configure multiple resourcesettings to a WTRU. In each resource setting, multiple CSI-RS resourcesmay be configured and each CSI-RS resource may correspond to one Txbeamformer. Each resource setting may correspond to one Tx beam group.For example, there may be two resource settings configured to a WTRU.The two resource settings may be linked to one reporting setting. TheCSI reporting setting may configure the WTRU to measure CSI-RS resourcesin both resource settings and report one or more CSI-RS resource indicesfor both resource settings. In an example, the two resource settings maybe linked to two or even more reporting settings. Each reporting settingmay be aperiodic, semi-persistent or periodic.

In an example, each CSI-RS resource may contain more than one antennaport. In this case, multiple antenna ports of a CSI-RS resource maycorrespond to one TX beam or multiple TX beams. If a CS-RS resource withmultiple antenna ports may represent multiple TX beams, TX beam groupingmay be supported. For example, one subset of antenna ports of multipleCSI-RS resources may represent one TX beam group, which may betransmitted from one antenna panel of a TRP, and another subset ofantenna ports of the same multiple CSI-RS resource may represent anotherTX beam group, which may be transmitted from another antenna panel ofthe same TRP.

A TRP may configure the resource settings to a WTRU by synchronizationsignal blocks (SSBs). The SS blocks may be grouped similarly so that oneset or one group of SS blocks are transmitted from one TRP panel, andanother set or group of SS blocks are transmitted from another TRPpanel. For a multi-panel WTRU, there may be multiple links between theWTRU and one TRP, or between the WTRU and multiple TRPs. In the case ofmultiple TRPs, the measurement and reporting configuration may beconfigured independently for each connected TRP. In this case, theconfiguration of each TRP may contain a high layer parameter todifferentiate different TRPs, For example, an identification index maybe included in the configuration IE.

For a multi-panel WTRU, there may be multiple links between the WTRU andone TRP, or between the WTRU and multiple TRPs. In the case of multipleTRPs, the measurement and reporting configuration may be jointlyconfigured for all connected TRPs. In this case, a list of involved TRPsmay be dynamically signaled and configured to differentiate the beamsfrom different TRPs while the WTRU performs independent or joint beammeasurement and reporting.

Procedures are described herein for beam measurement and reporting. Inan example, a WTRU may be configured with one or more resource settingsand/or one or more reporting settings. The WTRU may then perform thebeam measurement and reporting. WTRU beam measurement may be periodic,semi-persistent or aperiodic. Based on certain defined rules, a WTRU maydecide to report the measurement results after condition evaluations.When a multi-panel WTRU performs beam measurements, the WTRU may performdifferent types of beam sweeping based on the number of TRPs, TRP panelsand WTRU panels that are involved in the measurement process. Forexample, joint beam sweeping or independent beam sweeping may beperformed. In another example, same WTRU panel beam sweeping or acrossWTRU panels beam sweeping may be performed. In another example, same BWPbeam sweeping or across BWPs beam sweeping may be performed. In anotherexample, partial (selected) TRP-level beam sweeping or global TRP-levelbeam sweeping may be performed. In an example case for a WTRU to performbeam measurement reporting may be that CSI-RS resources are measured andreported in an aperiodic fashion to refine coarse beams identifiedthrough SS block measurements (e.g., periodically), thus avoidingconfiguring CSI-RS to sweep the entire coverage area for multiple TRPsor/and multiple TRP panels.

In order to reduce the overhead (e.g., transmission overhead at theTRP/gNB and/or measurement overhead at the WTRU) and latency (e.g.,number of swept beams at both the TRP and the WTRU), the different typesof beam sweeping may be flexibly and dynamically used according todifferent application scenarios and radio environment.

In order to achieve goals such as interference avoidance betweendifferent TRPs or between different antenna panels and/or flexiblecell/TRP coverage, the transmission power of the same or different DLreference signals (e.g., SSB, CSI-RS) from the same or different TRPs,or different panels of the same TRPs, may be dynamically changed. FIGS.13A and 13B show example network configurations 1300A and 1300B wheremulti-resolution and multi-reference based differential beam reportingprocedure may be used beneficially. FIG. 13A shows a network diagram ofan example network configuration 1300A including a WTRU 1304 and TRP1301 where different transmission power is used from TRP 1301 panels1311 and 1312 and FIG. 13B shows a network diagram of an example networkconfiguration 1300B where different transmission power is used from TRP1301 and TRP 1302. In these types of cases, the measured beam quality ata WTRU may have different ranges, for example, joint or independentmeasurement reporting for CSI-RS and SSB. To support differential beamreporting, multi-reference and/or multi-resolution based beam reportingmay be used.

For group based beam reporting, the reported beams within each grouprepresent the beams that may be received by a WTRU simultaneously.Within each group, the beam reporting may consider the following examplescenarios. For a DPS transmission scenario (e.g., only one TRP and/oronly one TRP panel is transmitting at a time), the WTRU may measure theTX beams and may report the best beam (e.g., in terms of measuredquality such as received signal strength indicator (RSSI), RSRP, SINRand/or RSRQ) for each TRP panel or each TRP independently. For anon-coherent joint-transmission scenario (e.g., more than one TRPsand/or more than one TRP panels are transmitting at a time), a WTRU mayreport the selected beams by considering the reported beam from each TRPor TRP panel is the best with respect to the same RX beam at the WTRU.In this case, the reported beams within each group may correspond to thebest beams in terms of best quality for a common RX beam (as in theexample FIG. 14A). For a non-coherent joint-transmission scenario, theWTRU may report the selected beams by considering the reported beam fromeach TRP or TRP panel is the ‘best’ with respect to a different DL RXbeam at the WTRU (as in the example FIG. 14B). In this case, thereported beams within each group may be selected such that interferenceis minimized. For example, the TX beams may be selected such that thecorresponding RX beams at the WTRU are separated as much as possible.FIG. 14A shows a network diagram of an example network configuration1400A where multiple DL TX beams at TRPs 1401 and/or 1402 correspond tothe same DL RX beams at the WTRU 1404. In the example networkconfiguration 1400A, DL TX beam 1 on TRP 1401 and DL TX beam 4 on TRP1402 may correspond to the same DL RX beam 3 of antenna panel 1421 atthe WTRU 1404. FIG. 14B shows a network diagram of an example networkconfiguration 1400B where multiple DL TX beams at a TRPs 1401 and/or1402 correspond to different DL RX beams at the WTRU 1404. In theexample network configuration 1400B, DL TX beam 2 on TRP 1401 maycorrespond to DL RX beam 2 of antenna panel 1421 at the WTRU 1404 and DLTX beam 2 on TRP 1402 may correspond to DL RX beam 2 of antenna panel1422 at the WTRU 1404.

In another example, the WTRU may report best beams independently foreach TX beam group configured in CSI-RS and/or SSB for beam management.In another example, the WTRU may report best beams jointly for all theTX beam groups configured in CSI-RS or/and SSB for beam management. Fornon-group based beam reporting, the reported beams may be selectedsimilar to the case in group based beam reporting.

For reduced latency and overhead, DL beam indication for PDSCH and/orPDCCH reception from multiple TRPs and/or multiple TRP/WTRU panels maybe achieved jointly or independently. In an example, an extension of TCIstate may be used such that each TCI state may be extended to supportbeam indication across multiple TRPs, multiple panels or/and multipleBWPs. Different CORESETs may be associated with the same or differentTCI states. To support dynamic beam switching (e.g., intra-panel,inter-panel, intra-TRP and/or inter-TRP switching) a CORESET may beassociated with multiple TCI states or the same TCI state with multipleRS set.

Although the features and elements described in the preferredembodiments may be described in reference to one or more particularcombinations, each feature or element can be used alone without theother features and elements of the preferred embodiments or in variouscombinations with or without other features and elements. Although thesolutions described herein consider LTE, LTE-A, New Radio (NR) or 5Gspecific protocols, it is understood that the solutions described hereinare not restricted to this scenario and are applicable to other wirelesssystems as well.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A multi-panel wireless transmit and/or receiveunit (WTRU) comprising: a transceiver; a processor; and a plurality ofantenna panels, each antenna panel comprising a respective plurality ofantennas, wherein the transceiver, the processor and the plurality ofantenna panels are configured to: send, to a transmission receptionpoint (TRP), antenna panel capability information for the plurality ofantenna panels; receive, from the TRP, a reference signal (RS)configuration for configuring RS resource sets, wherein the RSconfiguration includes time and frequency location information of theconfigured RS resource sets; receive, from the TRP, a first messageincluding an indication of RS resource sets from the configured RSresource sets and an indication of antenna panel identities (IDs) orbeam IDs associated with the plurality of antenna panels; and send,using a set of antenna panels from the plurality of antenna panels,reference signals using the indicated RS resource sets, wherein the setof antenna panels is determined based on the received RS configurationand the received first message.
 2. The WTRU of claim 1, wherein theplurality of antenna panels are homogeneous with similar transmit beamcapabilities or heterogeneous with different transmit beam capabilities.3. The WTRU of claim 2, wherein the transmit beam capabilities includeat least one of the following: a number of supported beams or amagnitude of directional coverage.
 4. The WTRU of claim 1, wherein theantenna panel capability information for the plurality of antenna panelsincludes at least one of the following: a number of WTRU antenna panels;antenna panel identifiers (IDs); or a number of supported beams for eachantenna panel.
 5. The WTRU of claim 1, wherein the RS configurationfurther indicates antenna panel IDs or directional beam IDs associatedwith the configured RS resource sets.
 6. The WTRU of claim 1, whereinthe indicated antenna panel IDs or beam IDs override previously signaledantenna panel IDs or beam IDS associated with the plurality of antennapanels.
 7. The WTRU of claim 1, wherein the transceiver, the processor,and the plurality of antenna panels are further configured to: receive,from the TRP, a second message including an indication of RS resourcesfor multi-panel uplink (UL) physical uplink shared channel (PUSCH)transmission using multiple antenna panels from the plurality of antennapanels.
 8. The WTRU of claim 1, wherein the RS is a sounding referencesignal (SRS).
 9. The WTRU of claim 1, wherein the transceiver, theprocessor, and the plurality of antenna panels are further configuredto: determine an uplink transmission beam sweeping mode based on the atleast one of the RS configuration of the first message, wherein thedetermined uplink transmission beam sweeping mode is one of a sequentialuplink transmission beam sweeping mode and a simultaneous uplinktransmission beam sweeping mode.
 10. A method, performed by amulti-panel wireless transmit and/or receive unit (WTRU) comprising aplurality of antenna panels, the method comprising: sending, to atransmission reception point (TRP), antenna panel capability informationfor the plurality of antenna panels; receiving, from the TRP, areference signal (RS) configuration for configuring RS resource sets,wherein the RS configuration includes time and frequency locationinformation of the configured RS resource sets; receiving, from the TRP,a first message including an indication of RS resource sets from theconfigured RS resource sets and an indication of antenna panelidentities (IDs) or beam IDs associated with the plurality of antennapanels; and sending, using a set of antenna panels from the plurality ofantenna panels, reference signals using the indicated RS resource sets,wherein the set of antenna panels is determined based on the received RSconfiguration and the received first message.
 11. The method of claim10, wherein the plurality of antenna panels are homogeneous with similartransmit beam capabilities or heterogeneous with different transmit beamcapabilities.
 12. The method of claim 10, wherein the antenna panelcapability information for the plurality of antenna panels includes atleast one of the following: a number of WTRU antenna panels; antennapanel identifiers (IDs); or a number of supported beams for each antennapanel.
 13. The method of claim 10, wherein the RS configuration furtherindicates antenna panel IDs or directional beam IDs associated with theconfigured RS resource sets.
 14. The method of claim 10, whereinindicated antenna panel IDs or beam IDs override previously signaledantenna panel IDs or beam IDS associated with the plurality of antennapanels.
 15. The method of claim 10, further comprising: receiving, fromthe TRP, a second message including an indication of RS resources formulti-panel uplink (UL) physical uplink shared channel (PUSCH)transmission using multiple antenna panels from the plurality of antennapanels.
 16. The method of claim 10, wherein the RS is a soundingreference signal (SRS).
 17. The method of claim 10, further comprising:determining an uplink transmission beam sweeping mode based on at leastone of the RS configuration or the first message, wherein the determineduplink transmission beam sweeping mode is one of a sequential uplinktransmission beam sweeping mode and a simultaneous uplink transmissionbeam sweeping mode.